Recent technological advances have enabled low-dose spiral CT to become an effective tool for lung cancer screening. The majority of pulmonary nodules detected on CT, however, are small and difficult to diagnose. While CT-guided transthoracic needle biopsy (CT-TTNB) has high diagnostic accuracy (70% to 90% depending on nodule size), the risk of complications such as pneumothorax and bleeding is high. Diagnostic confirmation by transbronchial lung biopsy using virtual bronchoscopy or electromagnetic navigation and endoscopic ultrasound is a safer alternative. However, the diagnostic yield is generally 10% to 20% lower than CT-TTNB. Current endoscopic ultrasound is limited by the size of the imaging probe, spatial resolution, and its inability to display blood vessels in the lesion. Furthermore, non-solid lung nodules are not well visualized by ultrasound. Owing to its large size, the ultrasound probe cannot be inserted through a biopsy needle or catheter. In lieu of this, a guide sheath is used to extend the working channel to allow insertion of biopsy forceps after removing the ultrasound probe to take a biopsy without-real time confirmation of the biopsy site. Therefore, there is an unmet clinical need for safe and accurate biopsy tools that can sample small pulmonary nodules under real-time image guidance. The goal of this project is to build and evaluate image-guided biopsy tools to address this knowledge gap. In Aim 1, we will develop a small optical coherence tomography (OCT) catheter that combines Doppler OCT with autofluorescence sensitive imaging. We will integrate these AF/OCT imaging catheters with biopsy tools that will enable localization and forward sample collection from lesions perpendicular to the airway as well as with side-collecting transbronchial biopsy tools in the wall of a bronchus parallel to the biopsy probe. Aim 2 is to evaluate, in a swine model, the feasibility and ability of the tools developed in the preceding aim to collect tissue samples with sufficient yield to enable standard and molecular pathology diagnosis and prediction of the biological behavior of malignant lesions.